System and Method for Managing Sleep Disorders

ABSTRACT

The present invention provides a method for managing a patient having a sleep disorder, e.g. sleep apnea, snoring, sleep bruxism, upper airway resistance syndrome, etc. The method comprises monitoring physiological information from the patient, converting the physiological information to digital data, storing the digital data in a digital memory, identifying and characterizing epochs based on the digital data, and storing the identifying and characterizing information of the epochs in a digital memory. The method further comprises organizing the epochs according to an organization function that considers at least characterization information of the epochs, selecting an epoch based on the organizing of the epochs, and generating sound derived from the stored digital data associated with the selected epoch such that the patient hears the sound. In a specific embodiment, the physiological information monitored may include sound, e.g. respiratory sound emanating from the trachea, and/or tooth-grinding sounds.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a continuation application claiming priority to U.S. patentapplication Ser. No. 11/139,294 filed May 27, 2005, commonly assigned,and hereby incorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

The present invention generally relates to health related disorders.More particularly, the invention provides a method and apparatus formanaging behaviors related to sleep disorders. Merely by way of example,the invention is applied using digital hardware and software.

Sleep apnea is a common disorder associated with severe adverse healthconsequences in some patients. It is generally recognized thatcontinuous positive airway pressure (CPAP) and other forms of positiveairway pressure (PAP) can be effective treatments for the obstructivetype of sleep apnea (OSA). Unfortunately, studies have found thatcompliance with CPAP among OSA patients is poor [L. GROTE, et. al.Therapy with nCPAP: incomplete elimination of sleep related breathingdisorder. Eur Resp J. 2000; 16:921-7.] [N. McARDLE, et. al. Long-termuse of CPAP therapy for sleep apnea/hypopnea syndrome. Am J Respir CritCare Med. 1999; 159(4 Pt 0:1108-14.].

The medical profession often views non-compliance or under-compliancewith advice/ecommendations from a healthcare professional asundesirable, i.e. a “negative” behavior on the part of the patient.Thus, there have been efforts to increase CPAP/PAP compliance among OSApatients. Some such efforts have, for example, employed alternate typesof facemasks, humidified air, alternate pressure schedules (e.g.bi-level positive airway pressure), and the like. Compliance-enhancingefforts have also included support or behavioral-cognitive elements [C.J. HOY, et. al. Can intensive support improve continuous positive airwaypressure use in patients with the sleep apnea/hypopnea syndrome? Am JRespir Crit Care Med. 1999; 159(4):1096-1100.]

In their review of CPAP compliance, Zozula and Rosen [R. ZOZULA, R.ROSEN. Compliance with continuous positive airway pressure therapy:assessing and improving treatment outcomes. Curr Opin Pulm Med. 2001;7(6):391-8.] observe: (1) Motivational factors are strongly associatedwith both acceptance of the diagnosis of OSA, as well as overalltreatment compliance; (2) Evidence suggests that patients' initialperception of improvement after initiating CPAP therapy is a strongpredictor of subsequent treatment compliance use; (3) Successfulcompliance is often affected by the type and degree of patient educationabout the specific medical condition; (4) Initial perceptions are oftendecisive; therefore the timing of an intervention aiming to increasecompliance is essential; (5) There is an increasing demand to findeffective interventions to increase CPAP compliance.

Zozula and Rosen further note that social-psychological models are usedwidely to account for patient behavior change in medical settings. Asone example, they summarize the “stages of change” model (usuallyattributed to Prochaska), in which individuals progress throughpredictable psychological stages in their efforts to adopt newhealth-related behaviors. Under the Prochaska model, a patient whotransitions to a stage characterized by greater readiness to change ismore apt to adopt new behaviors.

Issues of compliance and other patient behaviors are not restricted toOSA or CPAP. In general, any phase of a diagnostic or therapeuticprocess that requires action from a patient (or the patient's caretaker)may carry a risk of noncompliance. Some patients, for example, may delayaction until convinced they have a problem. Furthermore, convincing somepatients that they have a problem can be difficult, especially thoseunwilling to accept a physician's pronouncement of illness withoutaccompanying proof they can understand. This difficulty may be asignificant factor in many patients having a sleep disorder associatedwith no noticeable manifestations during or only minor noticeablemanifestations wakefulness.

In the case of snoring, recording and playing back the sounds of aperson's snoring have been used to prove to the person that they snore.There are limitations, however, to expanding the use of this techniquefor snoring and to extending this general approach to laypersons havingother sleep disorders such as sleep apnea.

For example, although the sound of snoring is generally recognizedcorrectly and readily by many laypersons, other abnormal sleep breathingevents (e.g. hypopneas and respiratory effort related arousals) mostlikely cannot be readily and correctly recognized from their sound bythe vast majority of laypersons without explanation or training. Thissuggests that mere audio recording and playback of sleep breathingsounds will have little influence on the behavior of an untrained laypatient who has a sleep disorder predominantly characterized by thesepathological events.

An additional shortcoming arises because events associated with sleepdisorders may vary in occurrence and severity during the course of asleep period. For example, a sleeping person may snore at some times andnot at others during the night. As an additional example, a sleepingperson may have frequent apneas in the hours just before awakening, butnot in the hours immediately after going to bed. Thus, propercharacterization of a patient's sleeping may require assessment of audiorecordings that span several hours of patient sleep time. Because humanattention spans are generally limited, most people are unlikely tolisten to such recordings for periods of hours.

From the above, it is desirable to have improved techniques for managinghealth related disorders. It is also desirable to have improvedtechniques to increase compliance with therapy and/or lead to otherdesired behavioral changes.

BRIEF SUMMARY OF THE INVENTION

According to the invention, techniques including a system and method formanaging certain types of behaviors in patients with a sleep disorderare provided. More specifically, the invention relates to a system andmethod for increasing the likelihood that a patient will adopt desirablebehaviors with respect to his or her sleep.

In a specific embodiment, the present invention provides a method formanaging a patient having a sleep disorder, e.g. sleep apnea, snoring,sleep bruxism, upper airway resistance syndrome, etc. The methodcomprises monitoring physiological information from the patient,converting the physiological information to digital data, storing thedigital data in a digital memory, identifying and characterizing epochsbased on the digital data, and storing the identifying andcharacterizing information of the epochs in a digital memory. The methodfurther comprises organizing the epochs according to an organizationfunction that considers at least characterization information of theepochs, selecting an epoch based on the organizing of the epochs, andgenerating sound derived from the stored digital data associated withthe selected epoch such that the patient hears the sound. In a specificembodiment, the physiological information monitored may include sound,e.g. respiratory sound emanating from the trachea, and/or tooth-grindingsounds.

Various additional objects, features, and advantages of the presentinvention can be more fully appreciated with reference to the detaileddescription and accompanying drawings that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one embodiment of a method for managing behaviors relatedto sleep disorders.

FIGS. 2A, 2B, and 2C show web pages that reflect organization of epochs.

FIG. 3 shows flowchart detail of an embodiment of organizing epochs.

FIGS. 4A, 4B, and 4C show web page front ends to a highlight reel.

FIG. 5 shows flowchart detail of preparing data for playback.

FIGS. 6A, 6B, 6C, and 6D show examples of dynamic graphical displayssynchronized to audio playback.

DESCRIPTION OF THE SPECIFIC EMBODIMENT

We have discovered that some persons who listen to selected sounds theymade while sleeping will, as a result the listening, change elements oftheir behavior in a positive direction (i.e. behave more in line withthe recommendations of a health care professional such as a physician).This discovery may be used in some cases to improve the management ofpatients with a sleep disorder.

We believe this phenomenon arises, at least in part, from the nature ofthe sounds and their emotional overtones. For example, in the case of aperson with sleep apnea, respiratory sound may vanish completely oralmost completely during an apnea. In the case of a person withobstructive sleep apnea, the relative quiet of an apnea may bepunctuated by “struggle sounds” (we prefer the term “quackles”) whichsound very much like choking noises. Persons with sleep apnea may alsohave post-apnea hyperventilation, the sound of which can sometimes givethe impression of almost-desperate attempts to catch one's breath.Similarly, in the case of sleep bruxism, the sound of teeth grinding maysometimes be distressing to a human listener.

Several sources teach the use of electronic equipment and respiratorysound in the diagnosis of sleep apnea, but fewer mention the playback ofrecorded sleep-breathing sounds to human ears.

Gavriely (U.S. Patient No. 6,168,568) teaches the playback of recordedbreath sounds to the operator of his invention, but does not describethe playback of recorded sound to the patient. He specifically mentions,as a feature of his invention, that playback of sound from his inventionmay be done while the patient is acoustically isolated from theinvention.

Sullivan (U.S. Pat. No. 5,989,193), Lynn and Lynn (U.S. Pat. No.6,223,064), and Raviv and Weingarten (U.S. Pat. Nos. 5,671,733;5,782,240; 5,879,313; 5,961,447; 6,045,514) teach listening to breathingsounds recorded from a sleeping subject, but only in the context of aphysician, clinician, or operator of their respective inventionsanalyzing potential breathing problems of the patient. Publications inthe medical literature teach playback of respiratory audio recorded froma sleeping patient, but, again, in the context of analysis; they do notmention playback to the patient or, in the case of children, to thepatient's parent [P. MARSH, et al. Recorder for assessment of upperairway disorders. Otolaryngol Head Neck Surg. 1983; 91:584-585.) (M. S.SCHECHTER, et al. Technical report: diagnosis and management ofchildhood obstructive sleep apnea syndrome. Pediatrics. 2002 April;109(4):e69.)

The present disclosure teaches a method and system for using sleepsounds to influence patient behavior. It aims to provide a flexible andefficient approach to acquiring, selecting, and delivering sounds thathave a high likelihood of positively impacting a patient behavior.

FIG. 1 shows one embodiment of a method for managing certain behavioralaspects of a sleep disorder in a patient. The patient may be anyorganism that sleeps. Certain steps depicted in FIG. 1 are amplified inlater figures.

One or more physiological and/or environment parameters related to thepatient are monitored 105. In cases where parameter values are in analogform, they may be converted 110 to data in digital form. For example,sound arising in the patient's airway may be picked up by a microphoneand converted into corresponding digital values by an analog-to-digitalconverter, with or without additional processing. Persons with ordinaryskill in the art will know of similar examples.

There are several possible patient parameters that may be monitored 105,including but not restricted to: electrocardiographic parameters,electroencephalographic parameters, electrooculographic parameters,myographic parameters, oximetric parameters, movement and locationparameters (e.g. body position, limb movement, chest motion, abdominalmotion), pressure and/or flow parameters (e.g. oronasal airflow,positive pressure delivery, esophageal pressure), gas exchangeparameters (e.g. end-tidal carbon dioxide concentrations), temperatureparameters, sound parameters (e.g. tracheal sound, tooth-grinding sound,musculo-skeletal sound, cardiovascular sound), parameters related to (orindicative of) arterial tone, and the like. Similarly, there are severalpossible environmental parameters that may be monitored 105, includingbut not restricted to: instrumentation-status parameters, noise (sound)parameters, ambient temperature and lighting, movement parameters, andthe like. If two patients share a sleep environment, physiologicalparameters of the first patient may sometimes be considered asenvironmental parameters for the second patient.

U.S. patent application Ser. No. 10/721,115, for example, teaches asystem and method for monitoring parameters related to tracheal sound,body position, arm movement, and battery voltage.

In one embodiment, some or all of the digital data are stored 115 indigital memory.

In one embodiment, epochs of data are identified and characterized 120.In this context, “identification” may refer to determining temporalboundaries that define an epoch of time, and “characterization” mayrefer to assigning attribute values reflecting the data associated withan epoch. For example, data obtained during a polysomnogram is oftendivided into 30-second epochs, i.e. each epoch normally has a start-timeand also has an end-time that is 30 seconds later. To continue theexample, a state of consciousness is normally assigned to each epoch onthe basis of epoch-associated polysomnographic data. (Wakefulness, stage1 sleep, stage 2 sleep, rapid eye movement sleep, etc. are examples ofstates of consciousness.) Thus, in this example, each 30-second epochcan be conceptualized as having an attribute calledSTATE-OF-CONSCIOUSNESS and for each epoch this attribute may take thevalues WAKEFULNESS, STAGE-1-SLEEP, etc.

Epochs may be defined by a start time and a stop time, or, equivalently,by a start-time and a duration. Times that define an epoch may beexpressed in absolute terms (e.g. as given by a clock) or in relativeterms (e.g. a quantity of time before or after a reference event). Inone embodiment, there is no requirement for epochs to be of uniformduration. Epochs of several durations may be present in a single patientstudy.

A plurality of attributes may be associated with a given epoch. We callthe set of all possible attributes and attribute values for epochs the“attribute scheme.” In some cases, the same information may be capturedwith different attribute schemes. For example, in some circumstances thetwo attribute schemes, A and B, below, capture approximately the sameinformation:

Attribute Scheme A Attribute Scheme B Attribute Possible ValuesAttributes Possible Values RESPIRATION- APNEA, APNEA YES, NO TYPEHYPOPNEA, HYPOPNEA YES, NO NORMAL NORMAL- YES, NO RESPIRATION

Different embodiments may use different attribute schemes. Merely by wayof example, attribute schemes may differ when different physiologicalparameters are monitored. In one embodiment, epoch attributes (but notattribute values) are pre-determined and stored in memory 190.

Possible epoch attributes include, but are not restricted to:

Attribute Possible Values RESPIRATION-TYPE APNEA, HYPOPNEA, RERA,NORMAL, OTHER SNORING YES, NO, BORDERLINE MOVEMENT-STATE TRANQUIL,RESTLESS ARM-MOVEMENT YES, NO, BORDERLINE BODY-POSITION FACE-UP,FACE-RIGHT, FACE-LEFT, FACE-DOWN BODY-POSITION-CHANGE YES, NO,BORDERLINE DOMINANT-FREQUENCY numerical value, in inverse time units(e.g. Hertz) SOUND-INTENSITY-MEAN numerical value, in sound intensityunits SOUND-INTENSITY- numerical value, in units derived VARIANCE fromsound intensity QUACKLES-PRESENT YES, NO, INDETERMINATE END-SNORT YES,NO, INDETERMINATE DESATURATION numerical value, in desaturation percentDESATURATION-SEVERITY NONE, MILD, MODERATE, SEVERE APNEA-TYPE CENTRAL,OBSTRUCTIVE, MIXED BRUXISM YES, NO, BORDERLINE TALKING YES, NO,BORDERLINE AIRWAY-RESISTANCE numerical value, in resistance unitsAIRWAY-HYPER- NONE, MILD, MODERATE, SEVERE RESISTANCE-SEVERITY PAP-MODENONE, CONTINUOUS, BILEVEL, AUTO, OTHER CPAP-PRESSURE numerical value, inpressure units (e.g. mmHg) MEAN-RESPIRATION- numerical value, in timeunits DURATION (e.g. seconds) AROUSAL YES, NO, BORDERLINE Note 1: Inthis table, when the “Possible Values” entry for an attribute consistsof comma-separated symbols all in capital letters, the symbols arepossible values of an enumerated set. When the “Possible Values” entryis in lower case, or mixed upper and lower case letters, the entrydescribes possible attribute values. Note 2: RERA stands for“respiratory effort related arousal,” a feature that has been seen inthe upper airway resistance syndrome.

Some attributes may take more than one value for a given epoch, e.g.under one attribute scheme a RESPIRATION-TYPE attribute for a certainepoch could simultaneously take both the SNORING and RERA values (sinceboth phenomena can occur simultaneously).

In one embodiment, all attributes could also take the valueINDETERMINATE or UNCERTAIN. In some embodiments, a measure of certaintymay be attached to attribute values. For example, a set of computercodes may classify an epoch's RESPIRATORY-TYPE as HYPOPNEA, but withonly 51% “confidence” that is the correct classification. In someembodiments, epoch attribute values may have associated confidencelimits, derived statistically.

In one embodiment, the duration of an epoch is not an attribute of theepoch; duration and start-time define an epoch. (Equivalently,start-time and stop-time define an epoch.)

Epochs may overlap in an embodiment. That is, a given point in time maybe included within the boundaries of a plurality of epochs. For example,20 minutes of monotonous uninterrupted snoring may be classified as oneepoch, and each of the individual snoring breaths within the 20 minutesmay also be classified as an epoch, and the inspiratory and expiratoryphases of each breath may themselves each be an epoch. As a furtherexample, epoch X may be defined to correspond to the period of apnea,and epoch Y may include both the period of apnea and the snort thatterminates the period of apnea.

Identification and characterization of epochs 120 may include dependentsub-steps. For example, the start and end times of epoch Y (seeparagraph above) can be determined with finality only when the beginningof the apneic period is known and the end of the snort is known.

Returning to FIG. 1, in one embodiment identification andcharacterization information produced by step 120 may be stored 125 inmemory.

In one embodiment, steps 105 through 125 may proceed at least partiallyin parallel. For example, identification and characterization 120 ofepochs associated with previously-acquired data may occur whilemonitoring 105 continues.

In one embodiment, organization of epochs 130 involves ranking and/orcollecting epochs. In one embodiment organization 130 of epochs occurson the basis of one or more attribute values of the epochs. Timingcharacteristics of an epoch may also be considered. In one embodimentorganization 130 is performed by applying an organization function (notshown in FIG. 1) to epochs stored 125 in memory. Merely by way ofexample, an organization function may be implemented as software codes.In another embodiment, organization 130 may be performed by a human. Instill another embodiment, both software codes and a human may beinvolved in the organization step 130.

In one embodiment, one or more epochs are presented 135 to a human in away that reflects some or all of the results of organization 130. Forexample, a computer interface may display a collection of epochs havingAPNEA as a value for the RESPIRATION-TYPE attribute. FIGS. 2A, 2B, and2C shows examples of web pages displaying information related toidentification, characterization, and organization of epochs in a sleepstudy (of unspecified type) performed on a patient named “Jim Smith.”FIG. 2A shows information about several categories of epochs, includingthe number and summed duration of all epochs within each category.(“Category” is an epoch attribute in the examples shown in FIG. 2,approximately corresponding to RESPIRATION-TYPE.) FIG. 2B showsinformation about a subset of epochs having the APNEA RESPIRATION-TYPE.FIG. 2C is the same as FIG. 2B, except that the epochs are sortedaccording to the value of epoch attribute END-SNORT (indicating whetheran apnea was terminated by a snort or not). In the sleep study shown,only one apnea epoch was terminated by a snort, and so it is listedfirst in FIG. 2C. Presentation 135 is an optional step.

Returning to FIG. 1, one or more epochs are selected 140 for playback150. In one embodiment, a human user makes the selection 140 inconjunction with presentation 135, e.g. using a mouse or other computerpointing device to indicate an epoch having a visible reference on aninteractive computer display. In another embodiment, a set of softwarecodes implemented on a digital computing device may perform selection140. Selection 140 may select a collection of epochs, rather than justone epoch. In one embodiment, selection 140 may select one or moreepochs.

An epoch selected in step 140 is prepared 145 for audio playback 150.Preparation 145 may employ data stored earlier (e.g. in step 115, instep 125, etc.); in cases where digital sound data were stored, suchdata may be retrieved and readied for conversion to (hearable) sound.

Preparation 145 assembles data associated with the selected epoch(s).For example, preparation 145 may retrieve tracheal sound datacorresponding to the selected epoch(s) and convert them into aQuicktime® audio file. Preparation 145 is discussed further inconnection with FIG. 5.

Playback 150 includes the actual generation of sound or other vibratoryphenomena.

A human (not shown in FIG. 1) listens to the sound played back 150. Thehuman is normally the patient, but may be a caretaker or loved one ofthe patient. Before hearing playback 150, the human may beconceptualized as being in a certain state A 160 with respect to his orher readiness to change one or more sleep-related behaviors. Afterhearing playback 150 and after receiving explanation 155 of the soundplayed back, the human may be conceptualized as being in state B 165with respect to his or her readiness to change one or more sleep-relatedbehaviors. Advice 170 to the human may further influence the human'sreadiness to change. In one embodiment, explanation 155 is optional.

In one embodiment “change” may include, but is not restricted to,altering, starting, and stopping. In another embodiment “behavior” mayinclude, but is not restricted to, decisions (e.g. to undergo or declinesurgery), externally visible actions, and mental actions (e.g. countingsheep as an insomniac might). In still another embodiment a“sleep-related behavior” may be a behavior that is expected to have aneffect on the sleep of the patient. (Note that sleep-related behaviormay occur during wakefulness).

Thus, examples of changes in sleep-related behavior include, but are notrestricted to: increasing compliance with a prescribed treatment for asleep disorder (e.g. continuous positive airway pressure, wearing of anoral appliance for the treatment of sleep bruxism or obstructive sleepapnea, sleeping with positional therapy, weight loss), increasingcompliance with a preventive regimen forestalling a sleep disorder (e.g.maintaining weight, avoiding alcohol near bedtime), and deciding toaccept more vigorous treatment of a sleep disorder (e.g. opting foruvulopalatopharyngoplasty as a surgical treatment for sleep apnea afterfailure of weight loss).

In one embodiment explanation 155 of the sound played back is brief andis delivered to the human at or near the time of playback 150. Forexample, after the sound of a hypopnea is played 150, the patient'sphysician could say to the human: “That was a near-stoppage ofbreathing” or, more dramatically, “That was a near choking.” We havefound that a short explanation is often adequate for even a lay humanlistener, as he or she can afterwards generally associate the sound witha past experience from life—often an experience with a significantemotional overlay (e.g. choking). There are several possible routes bywhich to deliver explanation 155, including, but not restricted to:orally, in print, by an animation, by a physical model, andelectronically (e.g. as on a computer or telephone display).

In one embodiment advice 170 may include, but is not restricted to, arecommendation from a health care professional, or an ostensibly neutralstatement of fact (e.g. “the mortality rate of the operation is 1%”)that may factor into one or more changes the human is contemplating.Advice 170 may be delivered by one or more routes, as was taught forexplanation 155.

Having transitioned to state B 165, the human may be confront the sameor different possible changes as in state A 160.

If multiple epochs are selected 140 in one embodiment, the order oftheir playback 150 optionally reflects a ranking within organization130.

The timing of playback 150 may be controlled in various ways. Forexample, the selection step 140, when performed by a human, may functionto initiate preparation 145 and playback 150 soon thereafter. In anotherexample, a separate trigger step (not shown in FIG. 1) may be employedbetween preparation 145 and playback 150, such that playback occurs onlywhen the trigger step has been completed (e.g. a human user indicates heor she is ready to hear the playback). As a further example, whenmultiple epochs are selected 140, their associated sounds may be playedback sequentially and uninterruptedly, or with a trigger step betweenepochs. FIG. 6A shows still another example of controlling playback 150:a computer interface with controls 610 that allow a user, among otheractions, to start and pause sound playback. Other approaches arepossible.

After listening to some or all sounds played back 150, the human may actin zero or more ways. For example, human 155 may deliver one or moreinputs (not shown in FIG. 1) to selection step 140 and/or organizationstep 130. Such input(s) may specify different epochs for playback 150 orreplay already-played sounds. Merely by way of example, such input(s)may occur through an interactive computer interface coupled to selectionstep 140 and/or organization step 130.

In one embodiment, organization 130 may involve ranking and/orcollecting epochs. In such an embodiment, ranking may involve anordering of epochs according to at least one or more attribute values,e.g. according to the value of the MEAN-SOUND-INTENSITY attribute;epochs may then be treated differently in subsequent processingdepending on their rank. Collecting may involve dividing a set of epochsinto subsets, e.g. according to the value of each epoch'sRESPIRATION-TYPE attribute; subsets may then be treated differently insubsequent processing. Organization 130 may include both ranking andcollecting, e.g. first creating collections of epochs according to theirRESPIRATION-TYPE, then ranking within each collection according toMEAN-SOUND-INTENSITY.

Organization 130 is often an important step. Some patients may havehundreds of epochs of abnormal breathing during a single night, e.g. apatient having severe obstructive sleep apnea. Determining which epochsand when the epochs should be played back 150 to the human may becomeimportant in cases where (a) all epochs cannot be reasonably played back(e.g. owing to limited human attention span) and (b) playback soundsassociated with different epochs have different effects on the human'sreadiness to change. We believe such cases are the norm.

FIG. 3 shows an embodiment of organization step 130. In this embodiment,an organizing function 305 performs the organization of epochs. It maydo so by considering attribute values associated with epochs, i.e. byranking and/or collecting epochs based on one or more of their attributevalues. Organizing function 305 may consider other information. Merelyby way of example, organizing function 305 may be implemented as a setof computer codes (e.g. software). In an embodiment where a plurality oforganization functions are possible, organizing function 305 shouldgenerally be chosen and/or configured 310 before use. In one embodiment,organizing function 305 may vary from invocation to invocation.Similarly, an embodiment may iteratively “evolve” an organizing function305.

In one embodiment, choosing and/or configuring 310 organizing function305 may be influenced by various factors. For example,choosing/configuring 310 may be performed on the basis of one or moreinputs 315 from a human user (e.g. a command to select only epochs witha RESPIRATION-TYPE of APNEA), from a database of user models 325, orfrom a database of algorithms 330. To choose or configure items from thedatabases (325, 330), it is possible to use inputs 315, characteristicsof the patient 320, and/or desired effects 335. Other approaches arepossible. We consider constructing and configuring an organizingfunction 305 as equivalent.

Characteristics 320 of the patient may derive from information obtainedduring monitoring 105 (e.g. characterized epochs 120) or other sources(e.g. age, sex, suspected sleep disorder).

In an embodiment a “user model” is an organizing function that has beenadapted for a specific listener (or group of listeners or class oflisteners). Thus, a user model may relate one or more characteristics ofthe patient (plus/minus the human listener, if different), an effect,and one or more possible organizing functions (or templates fororganizing functions). For example, one user model might represent theheuristic “If the patient has a known diagnosis of obstructive sleepapnea (OSA) and is not compliant with CPAP therapy, then organize epochsso that the most distressing epoch-sounds compatible with OSA are giventhe highest priority (so that the patient will be scared into complyingwith CPAP afterwards).” In this example, “diagnosis of OSA” and“noncompliant with CPAP” are characteristics of the patient,“prioritizing distressing sounds compatible with OSA” refers to apossible organizing function, and “complying with CPAP afterwards”refers to an effect. (All of a user model's relations need not beexplicit.)

Thus, in an embodiment it is possible to choose user model(s) fromdatabase 325 that have patient characteristic(s) and/or effect(s) whichmatch supplied patient characteristics 320 and desired effects 335. Inone embodiment, user models may be implemented as software objects.

A potential advantage of embodiments of the present invention isflexibility in determining which epoch-associated sounds to playback150. For example, separate user models may be implemented for snorers,for children, for persons in denial, for tooth-grinders, forsleep-talkers, for persons with sleep apnea, and so on. Over time, usersof the invention may increase their ability to predict what types ofsounds are most likely to positively affect behavior in certain classesof patients. The ability of a component of the present invention toidentify and characterize epochs may be advantageous because it couldspare a human operator from the potentially tedious work of listening tohours of sleep sound in order to identify the most impactful subsets.

The invention aims to allow experimentation with heuristics fororganizing epochs. We have already discovered certain characteristics ofimpactful sounds, e.g. sounds similar to choking noises, soundsconveying a sense of abnormally high work of breathing, prolongedabsence of respiratory sound, and hyperventilatory sounds after a periodof absent or choking sound, among others. These sounds often carry anemotional overtone when perceived by an adult human. It is generallydesirable to present such impactful sounds to a patient before thepatient's attention span wanes or the patient's time with a healthcareprovider ends.

We have also found that tracheal sounds are a useful source of sleepbreathing sounds for playback 150. Tracheal sounds, when reproduced (towithin a reasonable degree of fidelity to the original sound) through aloudspeaker or through headphones, can frequently be impactful if thepatient has a sleep breathing disorder.

In one embodiment, selected epoch-associated sounds may be included in a“highlight reel” of a sleep study. The term is borrowed from sportsbroadcasting: a sports highlight reel normally consists of dramatic orotherwise noteworthy images, and comprises only a fraction of all imagescollected during a sports contest.

By analogy, an embodiment of a highlight reel for a sleep study willusually contain dramatic or noteworthy occurrences found in the playbackaudio associated with the sleep study. There are several possibledefinitions for “dramatic” and “noteworthy” in this context; suchdefinitions may be implemented as user models or algorithms, as notedabove. For example all other factors being equal, an apnea havingstruggle sounds is often more dramatic sounding than one that does not,a louder snore is generally more dramatic sounding than a softer snore,and so on.

In one embodiment, the contents of a highlight reel of a study isdetermined via one or more organization steps 130, possibly with the aidof a user model. In one embodiment the results of one or morepreparation 145 steps become the highlight reel. A highlight reel maycontain images in addition to sound, similar to the playback step 150.

A highlight reel may be composed automatically (e.g. by a computer),manually (e.g. by a physician), or a combination of both. For example, ahuman may edit or approve the contents of a highlight reel compiled orproposed by a computer.

In one embodiment the highlight reel contains epoch-related data thatare anticipated to have the highest (or a significant) effect oninfluencing the behavior of the human that listens to (and possiblywatches) the highlight reel. In many cases, the highlight reel will berelatively short when compared to the duration of the sleep study. Ahighlight reel offers a venue for the concentration of the mostimpactful sounds identified in a sleep study.

FIGS. 4A, 4B, and 4C show examples of web page front-ends to the samehighlight reel. The highlight reel is derived from a sleep study (ofunspecified type) performed on a patient named “Jim Smith.” In FIG. 4Athe user may play the entire 2 minute 7 second highlight reel with theclick of a single button. In FIG. 4B the web page enumerates all 6epochs within the highlight reel and allows random-access control ofplayback for individual epochs. In FIG. 4C the web page enumerates allepochs within the highlight reel and allows serial-access control ofplayback for individual epochs.

FIG. 5 shows an embodiment of preparation step 145 in which it isdecomposed into sub-steps.

After receiving a reference to an epoch from selection step 140,information retrieval step 510 may retrieve epoch-related digital data(stored in step 115) and/or epoch-related attributes and attributevalues (stored in step 125).

In one embodiment, context generation 515 may occur. Here, “context”refers to those elements of an epoch's playback that are, strictlyspeaking, outside the temporal boundaries of the epoch. For example, ifan epoch of apnea is to be played back, the audio data corresponding tothat epoch may be nearly silent (because apnea can be nearly silent). Ahuman listener may better appreciate the significance of the silence ifadditional sound is presented, e.g. the sound made in the few secondsbefore the apnea and the few seconds after the apnea. In this example,these few seconds of sound are “context” for the apnea epoch. Thus,context generation 515 is an optional step that may add additional datafor playback of an epoch.

In one embodiment, synthesis 520 uses data retrieved in step 510 tocreate an intermediate digital representation (IDR) of the playback. TheIDR contains audio data that may later be rendered into sound. Forexample, synthesis 520 may generate a file formatted for playback usingQuicktime®, Windows Media Viewer, Real Player, Flash, or a structuredvector graphics player, etc. In one embodiment, audio elements such asnarration may be added to the IDR. Graphical elements may optionally beincluded as well. When included, certain graphical elements mayoptionally change appearance in synchrony with certain audio elements.

Optionally, the IDR may be copied 525 to a non-volatile medium, e.g.audio tape, hard disk, optical disk, certain MP3 players, Apple® iPod,and the like. In one embodiment, IDRs corresponding to a plurality ofepochs may be so copied. In some cases, digital-to-analog conversion mayoccur (e.g. in copying to analog audio tape). Some persons may find itconvenient to be able to transport a playable version of one or moreepoch-associated playback sounds.

Optionally, the IDR may be distributed 530 over an electronic network(e.g. a local area network, the Internet, etc.), possibly in a streamingfashion.

Playback 150 takes the output of step 520 as its input. In cases wherethe input is in digital format, a digital-to-analog conversion willordinarily be necessary. During playback 150 sound is emitted, possiblywith an accompanying graphical display 545. We have found that soundderived from 16-bit digital sampling at 2000 Hz yields an acceptabletradeoff between storage space and fidelity.

In an embodiment where sound data were not stored in step 115,“sonification” of non-audio data may be performed as part of synthesis520. Sonification, i.e. the conversion of non-audio data into sound, maybe useful when it discloses a pattern or transient in time-varying datathat is detectable by the human ear/brain system.

As one example of sonification, oxygen saturation data acquired during asleep study may be used to modulate the frequency of an audible sound(e.g. a 440 Hz sine wave). For example, if the oxygen saturation leveldrops at some point, the frequency of a sine wave can be made to drop ata corresponding point. If the frequency change were above somethreshold(s), a human listener would be able to hear it. Rapidvariations in oxygen saturation might, therefore, be perceivable asrapid variations in the frequency of the sine wave. In one embodiment,modulation occurs at a faster rate than the sampling rate of theoriginal data, so that long segments of data may, after sonification,occupy a shorter time. As an additional example, a library of sounds maybe used for sonification, e.g. an epoch with a RESPIRATION-TYPE ofHYPOPNEA could be represented acoustically by emitting a hypopnea soundof the proper duration taken from the library of sounds. These aremerely examples.

In some cases, graphical displays can increase the clarity andinformativeness of audio playback 150.

FIGS. 6A, 6B, 6C, and 6D show examples of graphical displays 545associated with audio playback 150. FIG. 6A shows a window containing aQuicktime movie corresponding to an epoch of 0.3 minutes in duration.Horizontal axis 605 shows time in minutes. Standard Quicktime moviecontrols (e.g. rewind, play, and volume control) are at the bottom ofthe window in region 610. The envelope of the epoch's associated audiosignal is plotted as a line 615, with vertical axis 606 showingincreasing sound intensity toward the top. Three peaks in the line 615a, 615 b, and 615 c correspond to sounds associated with individualbreaths taken by the patient. A sweep bar 620 moves from left to rightacross the window when the audio signal is played back 150. Its positionin the window at a particular moment corresponds to the portion of theepoch's audio that is playing at that moment. Thus, the graphicaldisplay of FIG. 6A is synchronized to sound emission 150.

FIG. 6B is similar to FIG. 6A in showing a sweep bar 630 in a Quicktimemovie window that plots the envelope 635 of an audio signal.Additionally, however, it shows an alphanumeric attribute value,“APNEA,” as a legend 640 in the window. The legend is visible onlyduring the time the sweep bar (and, therefore, audio playback) is withinthe time boundaries of a period of apnea. The apneic period in FIG. 6Bextends from approximately minute 187.5 to 187.7 on the horizontal axis.When sweep bar 630 and audio playback 150 are at minute 187.9, forexample, the APNEA legend is not visible (because the patient was notapneic at that time). A precise synchronization between graphicaldisplay and audio playback may assist humans in understanding the soundsthey hear.

FIG. 6C illustrates a graphical display containing more than envelopeand timing information. Time (in minutes) runs across the horizontalaxis. The sound envelope is plotted as a blue line 645, and oxygensaturation in the patient's blood is plotted as a red line 650(according to the vertical-axis scale 651 on the right). Arm movement ofthe patient is indicated by light blue shading 655 above the level ofthe envelope 645. Red shading 660 below the level of the envelope 645indicates snoring sound. The sweep bar 665 is present as a verticalblack line. U.S. patent application Ser. No. 11/095,154 teaches asimilar approach to data visualization.

FIG. 6D shows that multiple data channels (as in FIG. 6C) can beseparated into non-overlapping subplots, e.g. body position 670, soundenvelope 671, oxygen saturation 672, and pulse 673. All plots have thesame time (horizontal) axis, upon which the sweep bar 675 is based.

Although FIG. 6 uses a sweep bar, other interface constructs may performsimilar functions.

The present invention may be applied, for example, in a standalone sleeplaboratory in conjunction with polysomnography, or in cases where thepatient is tested in his or her home using a portable diagnostic device.U.S. patent application Ser. No. 11/095,154 teaches a method and systemcompatible with the current invention.

We have discovered several potential advantages of playing backsleep-related sound as an intervention to affect a patient's behavior.These potential advantages include, but are not restricted to: (1)Timing: The intervention can be applied early in the patient's course,e.g. almost immediately upon notifying the patient of the diagnosis; (2)Simplicity: Given elements of the present invention, the interventioncan be simple to perform; (3) Impact: The intervention can have apowerful impact on the patient, e.g. an emotional impact; (4) Retention:The intervention is in many cases inherently memorable; (5) Expense: Itis possible to implement the intervention inexpensively in comparisonwith the cost of protracted teaching by health care professionals; (6)Language independence: Although the intervention will usually requiresome communication with the patient in a language he or she understands,the crux of the intervention is generally sounds that are independent ofthe patient's ability to speak a given language (e.g. the language ofthe health care professional interacting with the patient).

It should be noted that the above sequence of steps is merelyillustrative. The steps can be performed using computer software orhardware or a combination of hardware and software. Any of the abovesteps can also be separated or be combined, depending upon theembodiment. In some cases, the steps can also be changed in orderwithout limiting the scope of the invention claimed herein. One ofordinary skill in the art would recognize many other variations,modifications, and alternatives. It is also understood that the examplesand embodiments described herein are for illustrative purposes only andthat various modifications or changes in light thereof will be suggestedto persons skilled in the art and are to be included within the spiritand purview of this application and scope of the appended claims.

What is claimed is:
 1. A system for communicating information about apatient's sleep, the system comprising: a memory for storing in digitalformat sound information spontaneously emitted from a patient during aperiod of time associated with a sleep period of the patient; means fordividing a portion of the period of time associated with the sleepperiod into a plurality of epochs, each of the plurality of epochshaving an attribute, the attribute being the same for each of theplurality of epochs; means for determining a value of the attribute foreach of the plurality of epochs; means for selecting an epoch in whichthe value of the attribute satisfies a specified criterion; means forretrieving from the memory the sound information associated with theselected epoch; means for converting the retrieved sound informationinto an analog form, means for outputting the analog form of theretrieved sound information to a listener.
 2. The system of claim 1wherein the means for selecting an epoch includes a user interface. 3.The system of claim 2 wherein the user interface displays references toepochs of the period of time associated with the sleep period.
 4. Thesystem of claim 3 wherein the user interface further displaysinformation about a value of an attribute of a plurality of epochshaving references displayed.
 5. The system of claim 4 wherein thedisplay of references to epochs is organized based on the value of anattribute of the epochs.